Fix for "Stock item for Product is not valid" error in Magento 1.x. It reproduces cataloginventory_stock_item using product entities.

magento_fix_stock_items.sql

INSERT INTO `cataloginventory_stock_item` (
`item_id` ,
`product_id` ,
`stock_id` ,
`qty` ,
`min_qty` ,
`use_config_min_qty` ,
`is_qty_decimal` ,
`backorders` ,
`use_config_backorders` ,
`min_sale_qty` ,
`use_config_min_sale_qty` ,
`max_sale_qty` ,
`use_config_max_sale_qty` ,
`is_in_stock` ,
`low_stock_date` ,
`notify_stock_qty` ,
`use_config_notify_stock_qty` ,
`manage_stock` ,
`use_config_manage_stock` ,
`stock_status_changed_auto` ,
`use_config_qty_increments` ,
`qty_increments` ,
`use_config_enable_qty_inc` ,
`enable_qty_increments` ,
`is_decimal_divided`
)
SELECT NULL ,  entity_id,  '1',  '1',  '0.0000',  '1',  '0',  '0',  '1',  '1.0000',  '1',  '0.0000',  '1',  '1', NOW( ) , NULL ,  '1',  '1',  '1',  '0',  '1',  '0.0000',  '1',  '0',  '0' FROM `catalog_product_entity`;

Thanks for this! I needed to use "INSERT IGNORE INTO" because not all my products were messed up.